IMS Menopause Live

Role of breastfeeding in postmenopausal osteoporosis

09 January, 2017

Osteoporosis is a huge public health problem for menopausal women all over the world, both in developing and in developed countries. Roughly one in three menopausal women suffers from osteoporosis and one in two from osteopenia. Prevention is the main stay for osteoporosis. It is very important to study all aspects of a woman’s life that can lead to later development of postmenopausal osteoporosis.

Osteoporosis has been studied extensively in relationship to ethnicity, geographical variations and estrogen depletion in menopause. However, the negative relationship of lactation duration and effect of pregnancies with postmenopausal osteoporosis is still inconclusive. The definite role of hormone replacement therapy in the prevention of osteoporosis is now a resolved issue. In a study by Hwang and colleagues [1], a cross-sectional survey based on the Korea National Health and Nutrition Examination Survey (KNHANES) 2010 and 2011 data (n = 1222 postmenopausal women), showed that a duration of breastfeeding longer than 37 months was associated with higher prevalence of osteoporosis in postmenopause and more fractures of the lumbar spine. A duration of lactation longer than 37 months was associated with low bone mineral density (BMD) in the lumbar spine and hip; the number of spinal fractures was increased (37 or more months, odds ratio (OR) 3.292; 95% confidence interval (CI) 1.485–7.23). But, interestingly, the number of deliveries had no relationship with postmenopausal BMD.

Comment

A woman’s life is a continuous cycle and various landmark changes have an effect on later development of postmenopausal problems; osteoporosis is one of these debilitating diseases, leading to poor quality of life and mortality.

Except for the above study by Huang [1], additional studies have looked into the role of lactation in women and later development of osteoporosis. Grimes and Wimalawansa believe that not only duration and frequency of lactation and return of normal menses, but also pre-pregnancy weight are related with postmenopausal osteoporosis [2]. The conclusion of the authors was that the importance of lactation and its effect on postmenopausal osteoporosis are very aptly considered as a public health problem needing new policy decisions, and so more work is required in this area.

Another interesting study was conducted in Jordan [3]. Multiple regression analysis at different bone sites revealed that there was a negative effect associated with the number of children (live births) and frequency of lactation but it was only evident at the femoral neck. In the final multivariable logistic regression model of variables that rendered significantly independent risk factors after adjustment for age and body mass index, it was found that ever-lactation, frequent lactation for four or more times, a lactation interval of 1–6 months, and clinical hyperthyroidism were significant protective factors. The authors concluded that, although osteoporosis is a large public health problem, in this study the number of pregnancies in their multiparous female population showed a negative impact on femoral neck BMD; no evidence of increased risk of osteoporosis among ever-pregnant women was noted.

Another analysis of data from the Korean KNHANES study [4] has reported that a significant increase (two- to three-fold) in the risk of osteoporosis is apparent in postmenopausal women with prolonged breast-feeding histories (24 or more months), particularly in those with inadequate serum vitamin D levels and calcium intake (>800 mg/day).

KNHANES provided further information in postmenopausal women whose first delivery occurred at age 24–29 years, a period during which bone mass slowly accumulates to its peak value. These women had a significantly increased risk of osteoporosis compared to those who first gave birth after the age of 30 years [5]. Use of contraceptives and hormone therapy were associated with less risk of postmenopausal osteoporosis. Lower body mass index, later menarche, earlier menopause, and lower calcium intake were associated with higher risk of postmenopausal osteoporosis. There was no mention of lactation period as that was not taken into account in the study. So besides lactation, other factors can be responsible for postmenopausal osteoporosis.

All these studies bring us to a very important issue in the prevention of postmenopausal osteoporosis. Preventative strategies should start very early in the life cycle of a woman. But pregnancy is a landmark period during which all women contact their medical practitioners. Women should be vigilant about replenishing stores of calcium and vitamin D during pregnancy and prolonged lactation and they should be counseled about these issues. Women with low body mass index, late menarche, early menopause and those with low level of physical activity should also be followed up and advised accordingly. Other risk factors like smoking and alcohol intake should also be discussed in the context of postmenopausal osteoporosis. In postmenopause, a history of prolonged breast feeding should be taken into account.